Примеры к статье «Блоки и контекст»

demo01.rb

# encoding: utf-8

class Alpha

  attr_accessor :alpha

  def beta
    self.alpha = 1
    alpha = 2
  end

end

a = Alpha.new
a.beta
p a.alpha

demo02.rb

# encoding: utf-8

# a = 'INIT'

def alpha
  a ||= :a
  p [:alpha, a]
end

define_singleton_method :beta do
  a ||= :b
  p [:beta, a]
end

a = 'TEST'

alpha

beta

demo03.rb

# encoding: utf-8

a = 'A'
b = 'B'

2.times do |a|
  b = a
  p [a, b]
end

p [a, b]

demo04.rb

# encoding: utf-8

class Alpha

  def alpha
  end

end

a = Alpha.new

a.define_singleton_method :beta do
end

p a
p [a.class, a.class.instance_methods(false)]
p [a.singleton_class,
   a.singleton_class.instance_methods(false)]
p a.class.ancestors
p a.singleton_class.ancestors

demo05.rb

# encoding: utf-8

module Alpha

  @@alpha = 'A'

  def alpha= x
    @@alpha = x
  end

  def alpha
    @@alpha
  end

end

class Beta
  include Alpha
end

class Gamma
  include Alpha
end

b = Beta.new
g = Gamma.new

p b.alpha

b.alpha = 'B'
p g.alpha

demo06.rb

# encoding: utf-8

class Alpha

  @@alpha = 'A'

  def Alpha.alpha
    @@alpha
  end

  def set_alpha x
    @@alpha = x
  end

end

a = Alpha.new
a.set_alpha 'X'

p Alpha.alpha

class Beta < Alpha
  @@alpha = 'B'
end

p Alpha.alpha

demo07.rb

# encoding: utf-8

class Alpha

  ALPHA = 'A'

end

module Beta

  ALPHA = 'B'

  class Gamma < Alpha

    def Gamma.alpha
      ALPHA
    end

  end

end

p Beta::Gamma.alpha
p Beta::Gamma::ALPHA

demo08.rb

# encoding: utf-8

class Alpha
  attr_accessor :alpha
end

# alpha = 'a'
x = 'x'

a = Alpha.new
a.alpha = 'A'

a.instance_eval do
  p [alpha, x, self]
  self.alpha = x
end

alpha = 'a'

p [alpha, x, a]

demo09.rb

# encoding: utf-8

class Alpha
end

Alpha.instance_eval do
  def alpha
  end
end

Alpha.module_eval do
  def beta
  end
end

p [Alpha.methods(false),
   Alpha.instance_methods(false)]

demo10.rb

# encoding: utf-8

class Alpha

  def name_method name
    define_singleton_method name do
      "name: #{name}"
    end
  end

end

a = Alpha.new

a.name_method :alpha
a.name_method :beta

p [a.alpha, a.beta]

demo11.rb

# encoding: utf-8

def get_binding
  local = 100
  return binding
end

b = get_binding

b.eval 'p local'

demo12.rb

# encoding: utf-8

a = :start

t = Thread.new do
  sleep 1
  Thread.exclusive { p a }
end

a = :continue

t.join

demo13.rb

# encoding: utf-8

$a = :start

fork do
  sleep 1
  p $a
end

$a = :continue

Process.wait